Long-Baseline Neutrino Facility (LBNF) and Deep Underground Neutrino Experiment (DUNE) Conceptual Design Report, Volume 4 The DUNE Detectors at LBNF
A description of the proposed detector(s) for DUNE at LBNF
physics.ins-det↗
arXiv subjects
V. Bellini
Publications and source records attributed to V. Bellini.
First Measurement of the $Σ$ Beam Asymmetry in $η^{\prime}$ Photoproduction off the Proton near Threshold
The $Σ$ beam asymmetry in $η^{\prime}$ photoproduction off the proton was measured at the GrAAL polarised photon beam with incoming photon energies of 1.461 and 1.480 GeV. For both energies the asymmetry as a function of the meson production angle shows a clear structure, more pronounced at the lowest one, with a change of sign around 90$^o$. The observed behaviour is compatible with P-wave D-wave (or S-wave F-wave) interference, the closer to threshold the stronger. The results are compared to the existing state-of-the-art calculations that fail to account for the data.
nucl-ex↗
Evidence for narrow resonant structures at $W \approx 1.68$ and $W \approx 1.72$ GeV in real Compton scattering off the proton
First measurement of the beam asymmetry $Σ$ for Compton scattering off the proton in the energy range $E_γ=0.85 - 1.25$ GeV is presented. The data reveals two narrow structures at $E_γ= 1.036$ and $E_γ=1.119$ GeV. They may signal narrow resonances with masses near $1.68$ and $1.72$ GeV, or they may be generated by the sub-threshold $KΛ$ and $ωp$ production. Their decisive identification requires additional theoretical and experimental efforts.
nucl-ex↗
A Proposal for a Three Detector Short-Baseline Neutrino Oscillation Program in the Fermilab Booster Neutrino Beam
A Short-Baseline Neutrino (SBN) physics program of three LAr-TPC detectors located along the Booster Neutrino Beam (BNB) at Fermilab is presented. This new SBN Program will deliver a rich and compelling physics opportunity, including the ability to resolve a class of experimental anomalies in neutrino physics and to perform the most sensitive search to date for sterile neutrinos at the eV mass-scale through both appearance and disappearance oscillation channels. Using data sets of 6.6e20 protons on target (P.O.T.) in the LAr1-ND and ICARUS T600 detectors plus 13.2e20 P.O.T. in the MicroBooNE detector, we estimate that a search for muon neutrino to electron neutrino appearance can be performed with ~5 sigma sensitivity for the LSND allowed (99% C.L.) parameter region. In this proposal for the SBN Program, we describe the physics analysis, the conceptual design of the LAr1-ND detector, the design and refurbishment of the T600 detector, the necessary infrastructure required to execute the program, and a possible reconfiguration of the BNB target and horn system to improve its performance for oscillation searches.
physics.ins-det↗
Measurement of Parity-Violating Asymmetry in Electron-Deuteron Inelastic Scattering
The parity-violating asymmetries between a longitudinally-polarized electron beam and an unpolarized deuterium target have been measured recently. The measurement covered two kinematic points in the deep inelastic scattering region and five in the nucleon resonance region. We provide here details of the experimental setup, data analysis, and results on all asymmetry measurements including parity-violating electron asymmetries and those of inclusive pion production and beam-normal asymmetries. The parity-violating deep-inelastic asymmetries were used to extract the electron-quark weak effective couplings, and the resonance asymmetries provided the first evidence for quark-hadron duality in electroweak observables. These electron asymmetries and their interpretation were published earlier, but are presented here in more detail.
nucl-ex↗
Probing the Repulsive Core of the Nucleon-Nucleon Interaction via the 4He(e,e'pN) Triple-Coincidence Reaction
We studied simultaneously the 4He(e,e'p), 4He(e,e'pp), and 4He(e,e'pn) reactions at Q^2=2 [GeV/c]2 and x_B>1, for a (e,e'p) missing-momentum range of 400 to 830 MeV/c. The knocked-out proton was detected in coincidence with a proton or neutron recoiling almost back to back to the missing momentum, leaving the residual A=2 system at low excitation energy. These data were used to identify two-nucleon short-range correlated pairs and to deduce their isospin structure as a function of missing momentum in a region where the nucleon-nucleon force is expected to change from predominantly tensor to repulsive. Neutron-proton pairs dominate the high-momentum tail of the nucleon momentum distributions, but their abundance is reduced as the nucleon momentum increases beyond ~500 MeV/c. The extracted fraction of proton-proton pairs is small and almost independent of the missing momentum in the range we studied. Our data are compared with ab-initio calculations of two-nucleon momentum distributions in 4He.
nucl-ex↗
Dark matter search in a Beam-Dump eXperiment (BDX) at Jefferson Lab
MeV-GeV dark matter (DM) is theoretically well motivated but remarkably unexplored. This Letter of Intent presents the MeV-GeV DM discovery potential for a 1 m$^3$ segmented plastic scintillator detector placed downstream of the beam-dump at one of the high intensity JLab experimental Halls, receiving up to 10$^{22}$ electrons-on-target (EOT) in a one-year period. This experiment (Beam-Dump eXperiment or BDX) is sensitive to DM-nucleon elastic scattering at the level of a thousand counts per year, with very low threshold recoil energies ($\sim$1 MeV), and limited only by reducible cosmogenic backgrounds. Sensitivity to DM-electron elastic scattering and/or inelastic DM would be below 10 counts per year after requiring all electromagnetic showers in the detector to exceed a few-hundred MeV, which dramatically reduces or altogether eliminates all backgrounds. Detailed Monte Carlo simulations are in progress to finalize the detector design and experimental set up. An existing 0.036 m$^3$ prototype based on the same technology will be used to validate simulations with background rate estimates, driving the necessary R$\&$D towards an optimized detector. The final detector design and experimental set up will be presented in a full proposal to be submitted to the next JLab PAC. A fully realized experiment would be sensitive to large regions of DM parameter space, exceeding the discovery potential of existing and planned experiments by two orders of magnitude in the MeV-GeV DM mass range.
physics.ins-det↗
ICARUS at FNAL
The INFN and the ICARUS collaboration originally developed the technology of the LAr-TPC. Located the underground LNGS Hall-B, the ICARUS T600 detector has been performed over three years with remarkable detection efficiency featuring a smooth operation, high live time, and high reliability. About 3000 CNGS neutrino events have been collected and are being actively analyzed. ICARUS will now be moved to CERN for an extensive R&D program. The T600 detector will be overhauled and complemented with a similar T150 detector. These improvements are performed in collaboration with the LBNE experiment, of which several INFN Institutions are now members. As a novelty, a SC magnetic field of about 1 T will be introduced. During 2016 it is proposed to move the experiment to FNAL where short base line neutrino beams are available, complementing the approved MicroBooNe experiment which will start operation in 2014. The ICARUS detectors at FNAL will be an important addition since, in absence of anomalies, the signals of several detectors at different distances from the target should be a copy of each other for all experimental signatures. Due to the reduced mass, in MicroBooNE the anti-neutrino signal is too weak for a sensitive comparison. Hence, a definitive clarification of the LSND anomaly requires the exploration of the anti-neutrino signal provided by the much larger T600. The magnetic field will allow separating the anti-neutrino signal from the neutrino-induced background. It is proposed to expose the T600 at the Booster NuBeam at ~700 m from target; the T150 will be located at ~150 m. The T600 will also receive >10^4 nu_e events/year from the off-axis NUMI beam peaked around 1 GeV and exploitable to prepare for the LBNE experiment. The ICARUS teams are also interested in extending the participation to other short baseline neutrino activities collaborating with existing FNAL groups.
physics.ins-det↗
Measurement of the Parity-Violating Asymmetry in Electron-Deuteron Scattering in the Nucleon Resonance Region
We report on parity-violating asymmetries in the nucleon resonance region measured using $5 - 6$ GeV longitudinally polarized electrons scattering off an unpolarized deuterium target. These results are the first parity-violating asymmetry data in the resonance region beyond the $Δ(1232)$, and provide a verification of quark-hadron duality in the nucleon electroweak $γZ$ interference structure functions at the (10-15)% level. The results are of particular interest to models relevant for calculating the $γZ$ box-diagram corrections to elastic parity-violating electron scattering measurements.
nucl-ex↗
Measurement of the Σ beam asymmetry for the ω photo-production off the proton and the neutron at GRAAL
We report on new measurements of the beam asymmetry for ω photo-production on proton and neutron in Hydrogen and Deuterium targets from the GRAAL collaboration. The beam asymmetry values are extracted from the reaction threshold (E_γ = 1.1 GeV in the free nucleon kinematics) up to 1.5 GeV of incoming photon energy. For the first time both the radiative and the three-pion decay channels are simultaneously investigated on the free proton. Results from the two decay channels are in agreement and provide important constraints for the determination of resonant state contributions to the ω production mechanism. First experimental results on the deuteron allow the extraction of the Σ beam asymmetry on quasi-free nucleons. Comparison of the results for free and quasi-free kinematics on the proton shows a generally reasonable agreement, similar to the findings in pseudo-scalar meson photo-production reactions. For the first time measurements on quasi-free neutrons are available, showing that both the strength and the angular distributions of the beam asymmetry are sensibly different from the results on the proton target.
nucl-ex↗
New Measurements of the Transverse Beam Asymmetry for Elastic Electron Scattering from Selected Nuclei
We have measured the beam-normal single-spin asymmetry $A_n$ in the elastic scattering of 1-3 GeV transversely polarized electrons from $^1$H and for the first time from $^4$He, $^{12}$C, and $^{208}$Pb. For $^1$H, $^4$He and $^{12}$C, the measurements are in agreement with calculations that relate $A_n$ to the imaginary part of the two-photon exchange amplitude including inelastic intermediate states. Surprisingly, the $^{208}$Pb result is significantly smaller than the corresponding prediction using the same formalism. These results suggest that a systematic set of new $A_n$ measurements might emerge as a new and sensitive probe of the structure of heavy nuclei.
nucl-ex↗
Measurement of the Neutron Radius of 208Pb Through Parity-Violation in Electron Scattering
We report the first measurement of the parity-violating asymmetry A_PV in the elastic scattering of polarized electrons from 208Pb. A_PV is sensitive to the radius of the neutron distribution (Rn). The result A_PV = 0.656 \pm 0.060 (stat) \pm 0.014 (syst) ppm corresponds to a difference between the radii of the neutron and proton distributions Rn - Rp = 0.33 +0.16 -0.18 fm and provides the first electroweak observation of the neutron skin which is expected in a heavy, neutron-rich nucleus.
nucl-ex↗
The 2010 Interim Report of the Long-Baseline Neutrino Experiment Collaboration Physics Working Groups
In early 2010, the Long-Baseline Neutrino Experiment (LBNE) science collaboration initiated a study to investigate the physics potential of the experiment with a broad set of different beam, near- and far-detector configurations. Nine initial topics were identified as scientific areas that motivate construction of a long-baseline neutrino experiment with a very large far detector. We summarize the scientific justification for each topic and the estimated performance for a set of far detector reference configurations. We report also on a study of optimized beam parameters and the physics capability of proposed Near Detector configurations. This document was presented to the collaboration in fall 2010 and updated with minor modifications in early 2011.
hep-ex↗
New Precision Limit on the Strange Vector Form Factors of the Proton
The parity-violating cross-section asymmetry in the elastic scattering of polarized electrons from unpolarized protons has been measured at a four-momentum transfer squared Q2 = 0.624 GeV and beam energy E =3.48 GeV to be A_PV = -23.80 +/- 0.78 (stat) +/- 0.36 (syst) parts per million. This result is consistent with zero contribution of strange quarks to the combination of electric and magnetic form factors G_E^s + 0.517 G_M^s = 0.003 +/- 0.010 (stat) +/- 0.004 (syst) +/- 0.009 (ff), where the third error is due to the limits of precision on the electromagnetic form factors and radiative corrections. With this measurement, the world data on strange contributions to nucleon form factors are seen to be consistent with zero and not more than a few percent of the proton form factors.
nucl-ex↗
Evidence for Narrow N*(1685) Resonance in Quasifree Compton Scattering on the Neutron
The first study of quasi-free Compton scattering on the neutron in the energy range of $E_γ=0.75 - 1.5$ GeV is presented. The data reveals a narrow peak at $W\sim 1.685$ GeV. This result, being considered in conjunction with the recent evidence for a narrow structure at $W\sim 1.68$GeV in the $η$ photoproduction on the neutron, suggests the existence of a new nucleon resonance with unusual properties: the mass $M\sim 1.685$GeV, the narrow width $Γ\leq 30$MeV, and the much stronger photoexcitation on the neutron than on the proton.
hep-ex↗
Effects of electronic correlation on X-Ray absorption and dichroic spectra at L$_{2,3}$ edge
We present a new theoretical approach to describe X-Ray absorption and Magnetic Circular Dichroism spectra in the presence of e-e correlation. Our approach provides an unified picture to include correlations in both charged and neutral excitations, namely in direct / inversion photoemission where electrons are removed/added, and photo absorption where electrons are promoted from core levels to empty states. We apply this approach to the prototypical case of L$_{2,3}$ edge of 3$d$ transition metals and we show that the inclusion of many body effects in the core level excitations is essential to reproduce, together with satellite structures in core level photoemission, the observed asymmetric line shapes in X-ray absorption and dichroic spectra.
cond-mat.mtrl-sci↗
Beam asymmetry $Σ$ measurements on the $π^-$ photoproduction off neutrons
The $Σ$ beam asymmetry in the photoproduction of negative pions from quasi-free neutrons in a deuterium target was measured at Graal in the energy interval 700 - 1500 MeV and a wide angular range, using polarized and tagged photons. The results are compared with recent partial wave analyses.
nucl-ex↗
Quantitative determination of spin-dependent quasiparticle lifetimes and electronic correlations in hcp cobalt
We report on a quantitative investigation of the spin-dependent quasiparticle lifetimes and electron correlation effects in ferromagnetic hcp Co(0001) by means of spin and angle-resolved photoemission spectroscopy. The experimental spectra are compared in detail to state-of-the-art many-body calculations within the dynamical mean field theory and the three-body scattering approximation, including a full calculation of the one-step photoemission process. From this comparison we conclude that although strong local many-body Coulomb interactions are of major importance for the qualitative description of correlation effects in Co, more sophisticated many-body calculations are needed in order to improve the quantitative agreement between theory and experiment, in particular concerning the linewidths. The quality of the overall agreement obtained for Co indicates that the effect of non-local correlations becomes weaker with increasing atomic number.
cond-mat.mtrl-sci↗